Avalanche Bulletin
更新日時: 2025/02/15 07:00
Niseko Yotei Yoichi Shiribeshi
Alpine Fair Moderate winds West winds will continue to build windslab
Treeline Fair Westerly winds and solar input contribute to slab formation
Below Treeline Good Solar input and rising temperatures will increase the reactivity of the storm slab.
信頼度：○ good □ Fair △ Low
Travel and Terrain Advice
Nicer weather today will permit travel higher in the mountains. Monitor rising temperatures and its impact on the snow. Look for wind and storm slab formation and any weak layers within the storm snow that may offer a failure plane for a slab avalanche to run on. Deep snow immersion, and buried tree bombs continue to be hazard today. Solar input will also cause new tree bombs to fall so look up when you travel through the forest and particularly when you take breaks.
Avalanche Problem
ウインドスラブ Wind slab
Moderate WNW winds through the day will continue to transport snow and build windslab and cornices.
ストームスラブ Storm slab
Sunny weather and rising temperatures will cause the storm snow to form into a slab today.
概要
Avalanche
A size 2 avalanche was ski cut on a North aspect of Shiribetsu yesterday. Also on Shiribetsu a skier accidental loose dry avalanche was triggered on an East aspect entraining significant amounts of snow and running to valley bottom. In the Kiroro region a natural size 1 storm slab was triggered by a tree bomb.
Snowpack
40-80cms of storm snow brings the total snow over the Jan. 28th PWL to 1-1.5 meters. Solar aspects also have a thin melt freeze crust that developed on Feb 8th and is ~1 meter deep. WNW winds have re-distributed storm snow causing cornice development and windslab formation on leeward aspects. Tests yesterday produced a hard, sudden planar compression test down 120cm SP result over the Jan. 28th layer indicating that this layer remains a factor but is buried deep and unlikely to trigger. The lower pack is well consolidated.
Weather
As a new low pressure system develops to the west of Hokkaido, today brings a break in the storm however winds will continue to be moderate from the NW. Overcast skies in the morning will give way to a mostly sunny day. No snowfall is expected today and valley temperatures will rise to +1C.
